Árpád Kovács

Integrating Functional MRI Information into Radiotherapy Planning of CNS Tumors-Early Experiences

The purpose of our study was to examine the integration of functional MRI (fMRI) information into 3D based planning process of the central nervous system (CNS) malignancies. Between 01.01.2008 and 01.12.2008 four patients with astrocytoma were enrolled to this study. Before the planning process conventional planning CT, postoperative MR and individual functional MRI examinations were delivered. For the functional MRI examination the following four types of stimulus were applied: acoustic, visual, somatosensory and numeral. Three different theoretical planning situations were applied and compared: 3D conformal plan without fMRI information, 3D conformal plan with fMRI information and IMRT plan with fMRI information. For plan comparison DVH analysis, and NTCP model were used. fMRI based OR definition resulted in 4 additional OR’s in the contouring process. As these cases demonstrate, an average of 50% dose reduction was achieved in OR, OR2 and OR3 with IMRT and fMRI based 3D planning, especially in case of midline localization and big tumor extent. IMRT provides additional sparing effect in the optic tract and brainstem, especially for localizations close to the midline. Our results demonstrated that using fMRI information in conventional 3D based treatment planning potentially benefits significant dose reduction in critical organs, with no compromise in PTV coverage. fMRI can be widely used even in low grade cases (long life expectancies, lower acute and late toxicity in radiotherapy) and in cases with high grade astrocytomas or metastases (higher dose to PTV with better risk organ sparing in radiotherapy).

Bi-exponential diffusion signal decay in normal appearing white matter of multiple sclerosis.

PURPOSE Our aim was to characterize bi-exponential diffusion signal changes in normal appearing white matter of multiple sclerosis (MS) patients. METHODS Diffusion parameters were measured using mono-exponential (0-1000 s/mm(2)) and bi-exponential (0-5000 s/mm(2)) approaches from 14 relapsing-remitting subtype of MS patients and 14 age- and sex-matched controls after acquiring diffusion-weighted images on a 3T MRI system. The results were analyzed using parametric or nonparametric tests and multiple linear regression models. RESULTS Mono-exponential apparent diffusion coefficient (ADC) slightly increased in controls (P=.09), but decreased significantly in MS as a function of age, nonetheless an elevated ADC was observed with increasing lesion number in patients. Bi-exponential analyses showed that the increased ADC is the result of decreased relative volume fraction of slow diffusing component (f(s)). However, the fast and slow diffusion components (ADC(f), ADC(s)) did not change as a function of either age in controls or lesion number and age in MS patients. CONCLUSIONS These data demonstrated that the myelin content of the white matter affects diffusion in relapsing-remitting subtype of multiple sclerosis that is possibly a consequence of the shift between different water fractions.

Thermoplastic Patient Fixation

Background and Purpose:Several methods have been developed to reduce tumor motions and patient movements during radiotherapy of lung cancer. In this study, a multislice CT-based analysis was performed to examine the effect of a thermoplastic patient immobilization system on the chest wall and tumor motions.Patients and Methods:Ten patients with stage II–IV lung cancer were enrolled into the study. According to tumor localization, five patients had peripheral, and five patients central lung cancer (T2–T4). In total, six series of measurements were made with a multislice CT scanner, both with and without mask fixation, in normal breathing, at maximal tidal volume inhalation, and at maximal tidal volume exhalation.Results:Movements of chest wall, diaphragm and tumor, with and without mask, under different breathing conditions were registered. With the use of the immobilization system, no significant difference was found in diaphragmatic movements (mean deviation of diaphragm: 41.7–40.5 mm to the right, and 40.5–36.8 mm to the left side) and in tumor motions (mean deviation of tumor: 15.3–12.4 mm in craniocaudal, and 11.5–8.8 mm in posterolateral direction, mean medial deviation: 4.6–4.1 mm, mean lateral deviation: 7.2–5 mm). Significant differences were observed concerning tumor motions in anteroposterior direction (mean: 8.9–6.3 mm) and transverse chest movements in anteroposterior direction.Conclusion:Besides the advantage of optimal patient positioning, the movements of the bony chest wall can be considerably reduced by using the immobilization system. However, this fixation system has limitations concerning its suitability for minimizing tumor motions.Hintergrund und Ziel:Zahlreiche Methoden wurden entwickelt, um die Tumor- und Patientenbewegungen während der Strahlentherapie von Lungenkarzinomen zu reduzieren. In dieser Studie wurde eine Mehrschicht-CT-basierte Analyse zur Untersuchung der Auswirkungen eines thermoplastischen Patientenimmobilisierungssystems auf die Thoraxwand- und Tumorbewegungen durchgeführt.Patienten und Methodik:Zehn Patienten mit Lungenkrebs Stadium II–IV wurden in die Studie eingeschlossen. Gemäß der Tumorlokalisation wiesen fünf Patienten ein peripheres und fünf Patienten ein zentrales Lungenkarzinom auf (T2–T4). Insgesamt wurden sechs Messserien mit einem Mehrschicht-CT-Scanner durchgeführt: mit und ohne Maskenfixierung, bei normaler Atmung sowie mit maximalem Atemvolumen bei Ein- und Ausatmung.Ergebnisse:Die Brustwand-, Zwerchfell- und Tumorbewegungen wurden mit und ohne Maske bei unterschiedlichen Atmungszuständen registriert. Bei Verwendung des Immobilisierungssystems wurden keine signifikanten Unterschiede in den Zwerchfellbewegungen (durchschnittliche Abweichung des Diaphragmas: 41,7–40,5 mm nach links und 40,5–36,8 mm nach rechts) und den Tumorbewegungen (durchschnittliche Abweichung des Tumors: 15,3–12,4 mm in kraniokaudaler und 11,5–8,8 mm in posteroanteriorer Richtung, durchschnittliche mediale Abweichung: 4,6–4,1 mm, durchschnittliche laterale Abweichung 7,2–5 mm) festgestellt. Signifikante Unterschiede waren bezüglich der Tumorbewegungen in anteroposteriorer Richtung (durchschnittlich 8,9–6,3 mm) und der transversalen Brustkorbbewegungen in anteroposteriorer Richtung zu beobachten.Schlussfolgerung:Neben dem Vorteil einer optimalen Patientenpositionierung können die Bewegungen der Thoraxwand mit Hilfe des Immobilisierungssystems erheblich reduziert werden. Dieses Fixierungssystem hat jedoch auch Grenzen hinsichtlich seiner Eignung zur Minimierung der Tumorbewegungen.

Thermoplastic patient fixation: influence on chest wall and target motion during radiotherapy of lung cancer.

Background and Purpose:Several methods have been developed to reduce tumor motions and patient movements during radiotherapy of lung cancer. In this study, a multislice CT-based analysis was performed to examine the effect of a thermoplastic patient immobilization system on the chest wall and tumor motions.Patients and Methods:Ten patients with stage II–IV lung cancer were enrolled into the study. According to tumor localization, five patients had peripheral, and five patients central lung cancer (T2–T4). In total, six series of measurements were made with a multislice CT scanner, both with and without mask fixation, in normal breathing, at maximal tidal volume inhalation, and at maximal tidal volume exhalation.Results:Movements of chest wall, diaphragm and tumor, with and without mask, under different breathing conditions were registered. With the use of the immobilization system, no significant difference was found in diaphragmatic movements (mean deviation of diaphragm: 41.7–40.5 mm to the right, and 40.5–36.8 mm to the left side) and in tumor motions (mean deviation of tumor: 15.3–12.4 mm in craniocaudal, and 11.5–8.8 mm in posterolateral direction, mean medial deviation: 4.6–4.1 mm, mean lateral deviation: 7.2–5 mm). Significant differences were observed concerning tumor motions in anteroposterior direction (mean: 8.9–6.3 mm) and transverse chest movements in anteroposterior direction.Conclusion:Besides the advantage of optimal patient positioning, the movements of the bony chest wall can be considerably reduced by using the immobilization system. However, this fixation system has limitations concerning its suitability for minimizing tumor motions.Hintergrund und Ziel:Zahlreiche Methoden wurden entwickelt, um die Tumor- und Patientenbewegungen während der Strahlentherapie von Lungenkarzinomen zu reduzieren. In dieser Studie wurde eine Mehrschicht-CT-basierte Analyse zur Untersuchung der Auswirkungen eines thermoplastischen Patientenimmobilisierungssystems auf die Thoraxwand- und Tumorbewegungen durchgeführt.Patienten und Methodik:Zehn Patienten mit Lungenkrebs Stadium II–IV wurden in die Studie eingeschlossen. Gemäß der Tumorlokalisation wiesen fünf Patienten ein peripheres und fünf Patienten ein zentrales Lungenkarzinom auf (T2–T4). Insgesamt wurden sechs Messserien mit einem Mehrschicht-CT-Scanner durchgeführt: mit und ohne Maskenfixierung, bei normaler Atmung sowie mit maximalem Atemvolumen bei Ein- und Ausatmung.Ergebnisse:Die Brustwand-, Zwerchfell- und Tumorbewegungen wurden mit und ohne Maske bei unterschiedlichen Atmungszuständen registriert. Bei Verwendung des Immobilisierungssystems wurden keine signifikanten Unterschiede in den Zwerchfellbewegungen (durchschnittliche Abweichung des Diaphragmas: 41,7–40,5 mm nach links und 40,5–36,8 mm nach rechts) und den Tumorbewegungen (durchschnittliche Abweichung des Tumors: 15,3–12,4 mm in kraniokaudaler und 11,5–8,8 mm in posteroanteriorer Richtung, durchschnittliche mediale Abweichung: 4,6–4,1 mm, durchschnittliche laterale Abweichung 7,2–5 mm) festgestellt. Signifikante Unterschiede waren bezüglich der Tumorbewegungen in anteroposteriorer Richtung (durchschnittlich 8,9–6,3 mm) und der transversalen Brustkorbbewegungen in anteroposteriorer Richtung zu beobachten.Schlussfolgerung:Neben dem Vorteil einer optimalen Patientenpositionierung können die Bewegungen der Thoraxwand mit Hilfe des Immobilisierungssystems erheblich reduziert werden. Dieses Fixierungssystem hat jedoch auch Grenzen hinsichtlich seiner Eignung zur Minimierung der Tumorbewegungen.

Development of monotectic surface layers by CO2 laser

The aim of our work was to develop a monotectic surface layer for be arings by using laser surface-treatment technology. Two kinds of laser surface t reatment technology were used. In case of coating-melting technology a Pb layer was first develope d by galvanization, then the Pb layer was melted together with the matrix. In case of powder bl owing technology Bi powder was blown into the layer melted by laser beam, by Argon gas. The struct ure of monotectic surface layer was investigated by light microscope and a scanning electron micros cope. The volume fraction and size distribution of Pb and Bi particles were determined by image-analyzer. Introduction The essence of laser alloying is that only structure and propertie s of the surface layer of specimen are changed, the structure and properties of the bulk part remains unchang ed. During development of monotectic surface layer, the surface workpiece is heated to a temperature, where only a single homogenous melt remains, in the system after alloying and then – beca use of good heat-extraction ability of the basic material it is quickly cooled. As a conse quence of the high cooling rate (100010000 K/s), a very fine structure develops during solidification. Experiments Laser experiments were performed in the Bay Zoltán Institute of Materials Science and Technology using a CO2 laser with a power of 5 kW. The basic alloy was an Al-11Si eutec tic type alloy. The thickness of specimen was 15 mm and the surface area treated by the laser was 15x130 mm . Two kinds of technologies were used for surface treatment [1-4]. Duri ng the two-step technology (melting of the coating) (Fig. 1) a Pb layer having a thickness of 0.1 mm was taken to the surface by galvanizing, then the Pb layer was melted together with the basic material by using different laser power (2, 2.5, 3, 3.5 kW). The sample was shifted by a scan velocity of 300 mm /min. During the treatment, 8 melted bands were with 50% overlap. Diameter of the foc us was 2 mm. Samples were coated with graphite before treatment to increase the low absorption of aluminium. During the one-step (powder-blowing-in) technology (Fig. 2) Bi grains w ith a diameter of 40-60 μm were blown into the molten layer. The protecting gas was Ar and the laser power wa s chosen (2, 2.5, 3, 3.5 kW). The sample scan velocity was 300, 600 and 900 mm/min respectively. Fi bands were melted on each sample with an overlap of 50%. Materials Science Forum Online: 2003-01-15 ISSN: 1662-9752, Vols. 414-415, pp 147-152 doi:10.4028/www.scientific.net/MSF.414-415.147

Effect of High Rotating Magnetic Field on the Solidified Structure of Al–7wt.%Si–1wt.%Fe Alloy

Al–7wt.-% Si–1wt.-% Fe alloy was solidified unidirectionally in the Crystallizer with High Rotating Magnetic Field (CHRMF). The diameter of sample was 8 mm and its length was 120 mm. The parameters of solidification were as follows: solid/liquid interface velocity ~0.082 mm/s, temperature gradient 7+/-1 K/mm, magnetic induction 0 and 150 mT, frequency of magnetic field 0 and 50 Hz. The structure solidified without rotating magnetic field (RMF) showed a homogeneous, columnar dendritic one. The structure solidified by using magnetic stirring showed a dual periodicity. On the one hand, the branches of the “Christmas tree”-like structure known from the earlier experiments contained Al+Si binary eutectic. On the other hand, bands with higher Fe- and Si-content formed in the sample, which were at a larger distance from each other than the branches of the “Christmas tree” structure. The developed microstructure was analyzed by SEM with EDS. The average Si- and Fe-concentrations were measured on the longitudinal section at given places along the length of sample. Furthermore the Si- and the Fe-concentrations close to the bands and among the bands as well as the composition of the compound phases were determined.

Application of MRI for improved local control in complex radiotherapy of cervical cancer

Background: The aim of this study was to analyze the use of magnetic resonance imaging (MRI) as a modern medical imaging technique in radiotherapy with special emphasis on the integration of MRI and a novel technique in brachytherapy to optimize treatment outcome in cervical cancer. Methods: In addition to the CT based shrinking volume conformal teletherapy in 31 patients with locally advanced cervical cancer, MRI examination with a special adjustable applicator at the treatment site was performed for the brachytherapy planning. To avoid excessive doses to the healthy structures during complex cervical radiotherapy isodose curves were calculated upon the information of the MR image and dose distribution was evaluated. Results: The consecutive application of CT and MRI limited the possibility for overdosage of the critical organs and undertreatment of the advanced tumor spread in all cases. The overall response rate for the complex treatment was 74.2% with complete regression in 25.8% of the cases. Based on the exact information of the three dimensional digital data radiation doses could be optimized without increasing the possibility of acute complications rate. Conclusion: The introduction of 3D treatment planning for teletherapy pelvic and boost irradiation of cervical carcinoma as well as for the brachytherapy part of the complex treatment is to be recommended. .

Examination of the Microstructure of the Findings from Cannon Foundry Sárospatak

The Rákóczi Museum of the Hungarian National Museum revealed a cannon casting foundry in the territory of the castle of Sárospatak. The excavation started in the summer of 2006. A great amount of findings were revealed from the metallurgical, alloying and casting processes of the foundry. The Archeometallurgical Research Group of the University of Miskolc examines the microstructure and the chemical composition of these findings. The aim of this research work is to complete the knowledge of the contemporary literature and reconstruct the technological processes of the foundry. In this article the current status of the examination is introduced.

Arrangement of the Al–Ni phases in Al/SiC(Ni)p composites

In the course of the production of Al/SiC composites made by powder metallurgical method, the interfacial bond between the reinforcing phase and the matrix is not acceptable in all cases. So the ceramic particles can suffer different kinds of damage by the stress which can mean the dropping out of the particles from the matrix, or their cracking. In order to improve the interfacial bond, the surface coating of the ceramic particles is recommended. One of the surface treatment methods is the electroless nickel plating (EN plating). The successfulness of the electroless nickel plating depends on the pre–treatment methods. By using the EN plated SiC particles in the Al/SiC composites, the nickel deposit of the silicon particles and the matrix can react with the formation of the different Al–Ni phases during the sintering. These phases were examined by scanning electron microscopy (SEM) and X–ray diffraction (XRD).

[Attendance in the second phase (2004-2005) of the Hungarian organized breast cancer screening program].

AIM Organised, nationwide screening for breast cancer with mammography in the age group of 45-65 years with a 2-year screening interval started in Hungary in January 2002. The aim of this study is to analyze the attendance rate of breast screening programme, including the analysis of the ratio of screening and diagnostic mammography examinations. DATA AND METHODS The data derive from the financial database of the National Health Insurance Fund Administration (NHIFA) covering the 6-year period between 2000-2006. The ratio of women in the age group of 45-65 years was calculated having either a screening mammography or a diagnostic mammography. The analysis was carried out for the years 2000-2001 before and 2002-2003, 2004-2005 after the implementation of nationwide organised programme. RESULTS In the years 2000-2001 7.26% of the women aged 45-65 had an opportunistic screening mammography, while in 2002-2003 34% and in 2004-2005 29.5% of the target population had screening mammography within the organised programme. During the same periods 19.8% (2000-2001), 22.1% (2002-2003) and 23.2% (2004-2005) of women aged 45-65 had a diagnostic mammography. Thus the total (screening and diagnostic) coverage of mammography increased from 26.2% (2000-2001) to 53.5% (2002-2003) and 50.8% (2004-2005). CONCLUSIONS Attendance of the Hungarian organised breast cancer screening programme slightly declined in 2004-2005, and to achieve the expected results in decline of mortality further improvement of attendance is necessary.